The Montgomery County Council on Tuesday passed legislation that will require payments or the replanting of trees lost from the tear down and “mansionization” of homes in older Bethesda and Chevy Chase neighborhoods.

The county’s Department of Environmental Protection (DEP) introduced the Tree Canopy Conservation bill last October, setting off months of debate between county government officials, home builders and conservationists on how far the bill should go.

County Executive Isiah Leggett argued home rebuilding projects in neighborhoods around Bethesda were leading to significant tree loss. Small building companies, many that do business in Bethesda and Chevy Chase, said the county shouldn’t be able to legislate how trees on private property are treated. Conservationists alleged the building industry was spreading misinformation about the bill.

In the end, the Council unanimously agreed on a bill that is very different from what DEP first proposed.

The measure approved on Tuesday will require builders to plant a certain amount of new canopy trees (or shade trees) on-site based on the amount of disturbance to existing trees.

For example, a project with a limit of disturbance (LOD) of 9,000 square feet of tree canopy would require nine new shade trees. If the builder only plants three, it would be required to pay $1,500 for the remaining six ($250 each) into a fund that the county would use to plant the trees off-site.

Before the vote, Councilmember Hans Riemer (D-At large) proposed going with a slightly different set of tree replacement requirements that would mean fewer shade trees and more ornamental trees. The proposal, which would have slightly lowered costs to builders, had the support of the building industry, but not all DEP officials or conservationists.

DEP officials have argued replacing an older shade tree with a smaller ornamental one would not achieve the same tree canopy that was lost from a homebuilding project.

“This is not the most enormous change in the world, but I still think it’s fundamentally wrong,” Councilmember Marc Elrich (D-At large) said. “The substituting of ornamental trees is like substituting in something that everybody does anyway.”

The Council voted down Riemer’s amendment 5-4.

Councilmember Roger Berliner (D-Bethesda-Chevy Chase) supported the all-shade tree approach, but indicated he would be content with either set of requirements.

“We are doing something that we have never done before,” Berliner said. “We are saying that trees on private property have a community value.”